The present invention relates to a luminaire for an elongate lamp, having longitudinal reflectors running parallel to the lamp and having a multiplicity of spaced-apart transverse lamellae which have a bottom, tapering region and of which the bottom edge is curved.
Such a luminaire is known from U.S. Pat. No. 5,758,954. The bottom, tapering region of the transverse lamellae here has a changing curvature since the bottom edge of the transverse lamellae is curved, whereas the edges which bound the bottom, tapering region in the upward direction are of rectilinear design. This geometry has an adverse effect on the lighting distribution.
The object of the invention is thus to improve the lighting distribution of the known luminaire.
This is achieved according to the invention in that the cross section of the bottom, tapering region is of the same shape over the width of the transverse lamellae, and in that the edges which bound the bottom, tapering region in the upward direction coincide, in terms of curvature, with the bottom edge of the transverse lamellae.
The three-dimensional shaping of the bottom region of the transverse lamellae is produced, from a geometrical point of view, in that a predetermined segment of a curve, which is preferably curved parabolically, is displaced in a plane normal to the longitudinal axis of the lamp, with constant alignment, along the curved bottom edge of the transverse lamellae. The highest point here is located in the center of the transverse lamellae, whereas the bottom edge slopes down in the direction of the borders of the transverse lamellae. The cross sections through the transverse lamellae are of the same shape and are merely offset in height in relation to one another. Overall, the new lamellae shape makes it possible to achieve, even with elongate light sources, for example fluorescent tubes, an essentially rotationally symmetrical light distribution and screen behavior.
It is particularly straightforward from a design point of view if the top region of the transverse lamellae, said top region being located above the edges, is of a constant thickness. It is favorable here from a lighting point of view if the thickness of the transverse lamellae is approximately half the diameter of the lamp.
Excess limiting of the radiation in the longitudinal direction of the luminaire can be avoided in that the vertical height difference of the bottom edge of the transverse lamellae is approximately a quarter of the diameter of the lamp.
In order to provide a free space for the lamp, finally, it is preferably provided that the top surface of the transverse lamellae, as seen in the longitudinal direction of the lamp, is indented in the form of a V in the central region.